Alistair's assessment is that the orb is both a construct and an autonomous magic item. It's definitely the source of the cold within the room and must be the "security system" the wraith mentioned previously. Given it didn't react to Alistair's voice, nor does it respond when anyone peeks around Levi's cover to survey the room, it must have some other detection method or its detection area may be limited to the area within the room. Nothing on its outer shell gives you any indication of what its detection method could be.

Its construction doesn't appear to be out of any kind of special metal or similar, so it's not likely to survive a significant amount of damage. Given the frozen delvers and its reaction time to the wraith peeking in, it's likely dangerous to approach it. Dispel Magic should be effective against it, though it would take a powerful caster to make something like this.

From its construction Alistair guesses that it likely fires beams of such concentrated cold energy that anyone hit freezes over on a failed Fortitude Save (the wraith was spared as objects don't get frozen, and if the wraith was frozen it would just pass through the ice).